It is generally considered poor form to begin a sentence with a numeric digit. For example,

4% of people are old.

should be

Four percent of people are old.

What is the rule when you need to begin a sentence with a chemical name that should not be converted to a word?

2-chloroprocaine is an anesthetic.

It doesn't seem right to capitalize the first letter after the number, because chemicals are not normally capitalized.

2-Chloroprocaine is an anesthetic.

Spelling it out seems inaccurate.

Two-chloroprocaine is an anesthetic.

Rewriting the sentence makes it confusing.

An anesthetic, 2-chloroprocaine, is.

  • 1
    This matter is one that would be ruled by the house style guide of the journal or publisher. My advice would be to go to such a journal and see how they do it. Here's an example where it begins the sentence: books.google.com/…
    – TimR
    Aug 7, 2017 at 20:17
  • As a frequent contributor to chemistry.se and ell, @M.A.R might have some insight...
    – Adam
    Aug 7, 2017 at 20:28
  • 1
    I am not aware of any rule about not starting sentences with a number. In your example, a general rule is to write out numbers less that ten, rather than use the numeral.
    – user3169
    Aug 7, 2017 at 20:54
  • 1
    Tempted to +1 this question based only upon your choice of J. R. "Bob" Dobbs as avatar. Aug 8, 2017 at 2:08

1 Answer 1


An article called Effects of Concentration and Volume of 2-Chloroprocaine on Epidural Anesthesia in Volunteers has a sentence beginning with the chemical, which is capitalized:

2-Chloroprocaine has different physicochemical properties (higher pKa and lower lipid solubility) than other commonly used local anesthetics.

Otherwise, it remains lowercase:

This study was performed to delineate effects of a threefold difference in concentration and volume of 2-chloroprocaine on sensory and motor block during epidural anesthesia in a crossover fashion.

  • This is completely correct.
    – user30379
    Aug 7, 2017 at 23:14

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